1. Field of the Invention
The invention relates to a method for solid-phase microextraction and analysis of substances originating for example from a carrier fluid and to a collector for use within this method. The invention also relates to a collector, which serves as a passive collector in a gaseous, for example loaded environment containing substances to be analyzed and a method for solid-phase microextraction and analysis of these substances.
2. Description of the Related Art
A method of this type is known from Boyd-Boland et al., Environ. Sci. Technol. Vol. 28, No. 13, 1994, 569A-574A and from EP 0,523,092 B1, in which a special syringe is used, which has a fiber which can be telescoped through the syringe needle. The fiber, which is expediently coated, is brought into contact with the carrier fluid which contains the substances to be examined and at the same time is being stirred, after which the fiber is retracted and the syringe needle is introduced into a feeding device of an analyzer, followed by desorption of adhering substances using a carrier gas. The fiber has only a very limited absorption capacity for substances which are to be examined and, moreover, is only dipped into the stirred carrier fluid, so that consequently the sensitivity of the analysis itself leaves something to be desired if the coated fiber is vibrated. In addition, it is known from DE 196 19 790 C2 to have the microfiber functioning as a collector rotate about its own axis by means of an electric motor with a rotational speed of one""s choice.
An object of the invention is to provide a method for solid-phase microextraction and analysis of substances to be analyzed and originating for example from a carrier fluid, which provides a significantly improved sensitivity.
Another object of the invention is to provide a collector for solid-phase microextraction and analysis of substances to be analyzed and originating for example from a carrier fluid.
A further object of invention is to provide a collector which may be used within the method for solid-phase microextraction and analysis of substances.
A still other object of the invention is to provide a collector as a passive collector for solid-phase microextraction and analysis of substances for example pollutants to be analyzed and originating for example from an environment.
A still other object of the invention is to provide a method for solid-phase microextraction and analysis of substances to be analyzed and originate from an environment, for example pollutants.
A subject of the invention is a method for solid-phase microextraction and analysis of substances in a carrier liquid, in which a collector is brought into contact with the stirred liquid containing the substances for a sufficient time and is then subjected to a solid-phase extraction directed at at least one substance adhering to the collector, and desorbed substances are transported for analysis by means of a carrier gas, wherein the carrier liquid containing the substances is stirred in a receptacle of a magnetic stirrer by means of a coated magnetic stirring element as collector, and/or the carrier liquid is made to move intimately relative to the collector by means of ultrasound, and afterwards the stirring element is arranged in a solid-phase extraction device.
Another subject of the invention is a collector for the solid-phase microextraction and analysis of substances to be examined, in particular for use in a thermal desorption apparatus of a gas chromatograph, comprising a carrier made from magnetic material, which is suitable as a stirring element for a magnetic stirrer and is provided with a sorbent and/or adsorbent coating for the substances to be examined.
A still other subject of the invention is a coated magnetic collector, which serves as a passive collector in a gaseous, for example loaded, environment containing substances to be analyzed.
A still other subject of the invention is a method for the solid-phase microextraction and analysis of substances in an environment, in which a collector is exposed to the environment for a sufficient time as a passive collector and then the collector is positioned in a solid-phase extraction device, desorbed substances being transported for analysis by means of a carrier gas.
The use of a stirring element which is actuated by a magnetic stirrer and/or an ultrasonic agitator increases the accuracy of analysis very considerably, and moreover it is possible to use large-volume receptacles, for example liter receptacles, for the fluid containing the substances to be examined.
Further objects, advantages and embodiments of the invention are evident from the following description.
The invention is explained in more detail below with reference to exemplary embodiments of the invention, which are illustrated in the attached drawings, of a device for carrying out the method and of passive collectors.